1. Field of the Invention
The present invention relates to a light source apparatus using a cone-shaped (also referred to as cone-like) material or element and an applied apparatus thereof such as illuminating apparatus or a display apparatus, in particular, a projection type display in combination of a display element having a transparent-scattering type operation mode and the above-mentioned light source apparatus.
2. Discussion of Background
FIGS. 23 through 26 show conventional techniques, and Tables 6 through 11 show comparison of the performance between the light source apparatus and the projection type display according to the present invention and the conventional technique.
First, the invention disclosed in Japanese Unexamined Patent Publication No. 113344/1992 is explained with reference to FIG. 26. In FIG. 26, a light source apparatus 100A comprises an elliptic mirror 12, a light source 11 disposed in the vicinity of the first focal point of the elliptic mirror 12 and a first aperture 17 disposed in the vicinity of the second focal point. Further, a projection type optical apparatus 150A comprises the light source apparatus described above and a transparent-scattering type display element and a projection optical system. This invention is to obtain parallel light fluxes having high collimation and luminous flux.
FIG. 24 shows the invention disclosed in Japanese Unexamined Patent publication No. 142528/1992 in which a light source apparatus 100B comprises a light source 11, an elliptic mirror 12, a prism 5 of a long rod-like shape and a first aperture 17 and an optical converging means 13. Further, a projection type display 150B comprises the above-mentioned light source apparatus, a transparent-scattering type display element 15, a second aperture 18 and a projection lens 19.
FIG. 23 is an enlarged cross-sectional view of the prism 5. The prism 5 is provided with convex conical surfaces 5a, 5b at the side into which light enters and a curved convex surface 5e at the side from which the light is emitted. The prism 5 has a long cone-shape wherein the thickness is gradually reduced from the light incident side to the light emission side so that the light is totally reflected many times at the slanted surface 5f in view of the inside of the prism 5.
The invention disclosed in International Publication Number WO92/16871 will be described with reference to FIG. 25. In FIG. 25, a light source apparatus 100C comprises a light source 11, a parabolic mirror 14 and two optical elements 6a, 6b each having a circular cone shape in cross section. Further, a projection type optical apparatus 150C comprises the above-mentioned light source apparatus, a transparent-scattering type display element and a projection optical system which is temporarily indicated in comparison with the structures of the present invention. The optical elements 6a, 6b are so disposed as to face the bottom surfaces whereby light fluxes pass parallel light paths. In this invention, substantially parallel light fluxes are obtainable without causing a shadow.
In the next, FIG. 1 of Japanese Unexamined Patent Publication No. 138410/1992 is referred to explain a conventional technique. In FIG. 1, there is shown a projection apparatus constituted by a light source emitting parallel light fluxes which comprises a light source, a first condenser lens and two cone lenses, a second condenser lens and a projection lens and so on. The subject of the disclosed invention is to obtain a projected image having a substantially uniform distribution of illuminance on a screen. The light source emitting parallel light fluxes is indicated by numeral 100D and the projection apparatus is indicated by numeral 150D which are temporarily indicated in comparison with the structures of the present invention.
FIGS. 1 and 2 of Japanese Unexamined Patent Publication No. 293547/1988 show an optical illuminating apparatus comprising two elliptic mirrors and a cone prism which functions as a light beam direction changing member. The subject matter of the invention is to obtain a light flux having a high luminous flux.
Further, in Nikkei Electronics, Vol. 494, p. 122, there is shown a full color projection type liquid crystal display apparatus comprising a color separating and synthesizing optical system having a light source and a dichroic mirror arranged to have an angle of incidence of 45.degree. to the light source and liquid crystal elements for R, G and B colors. The conventional apparatus which is temporarily indicated in comparison with the structures of the present invention is referred to as numeral 300.
In the above-mentioned conventional apparatuses, the light sources apparatuses 100A through 100D have such means that light emitted from the light source is adjusted in size and is introduced to the display element and so on whereby a light flux having an appropriate brightness is obtainable. Namely, efficiency of light utilization can be increased, and uniform light can be obtained by, for instance, moving in parallel a light path for a light flux from an actual lamp as a non-point light source.
In these conventional apparatuses, however, it was insufficient to obtain a uniform distribution of light energy irradiated to the display element from the light source system and good efficiency of light utilization while maintaining high collimation, because it was difficult to compensate sufficiently the reduction of efficiency of light utilization which was due to a distribution of light from a light emitting part having a finite length and non-uniformity of light fluxes, as well as difficulty in obtaining the light fluxes having a high collimation. For instance, the optical divergence total angle of the parallel light flux obtained by using a parabolic mirror was about 12.degree.-15.degree..
It is an object of the present invention to provide a light source apparatus having a high collimation of light, a uniform illuminance at an irradiation surface and a high luminous flux.
Further, it is an object of the present invention to provide a projection type display which is in combination of a transparent-scattering type display element having a high transparent characteristic and a high scattering characteristic and the light source described above, and which can achieve a high efficiency of light utilization and a high contrast ratio as well as a high uniformity of a projected picture image which could not be obtained by the conventional projection type display apparatuses.
Further, the present invention is to provide the projection type display apparatus having a small and rigid structure and is capable of adjusting the light flux and the contrast ratio for a projected picture image.
In accordance with the present invention, there is provided a first light source apparatus which comprises an elliptic mirror 12; a light source 11 disposed in the vicinity of the first focal point of the elliptic mirror 12; a cone-like material disposed in the vicinity of the second focal point of the elliptic mirror 12 so that the apex of the cone-like material is substantially on the optical axis of the same, and an optical converging means 13, whereby light emitted from the light source 11 is reflected and converged by the elliptic mirror 12 to be incidented into the cone-like material; the light is emitted through the conical surface of the cone-like material, and enters as divergent light into the optical converging means 13 by which the light is regulated to be substantially parallel light beams.
There is provided a second light source apparatus wherein in the first light source apparatus, the cone-like material is a convex cone prism 1 having an apex angle .alpha..sub.1 of 90.degree.-175.degree. in a plane sectioned to include the optical axis of the prism 1, and a flattened incident surface.
There is provided a third light source apparatus of the present invention wherein in the first light source apparatus, the cone-like material is a concave cone prism having an apex angle .beta..sub.1 of 185.degree.-270.degree. in a plane sectioned to include the optical axis of the prism 2, and having a flattened incident surface.
There is provided a fourth light source apparatus of the present invention wherein in the first light source apparatus, the cone-like material is a convex cone-like reflector 10 having an apex angle .alpha..sub.2 of 150.degree.-177.degree. in a plane sectioned to include the angular bisector between the incident optical axis and the output optical axis of the reflector.
There is provided a fifth light source apparatus of the present invention wherein in the first light source apparatus, the cone-like material is a concave cone-like reflector 20 having an apex angle .beta..sub.2 of 183.degree.-210.degree. in a plane sectioned to include the angular bisector between the incident optical axis and the output optical axis of the reflector.
In the present invention, there is provided a sixth light source apparatus wherein in any of the first through fifth light source apparatuses, the cone-like material is an apex angle the shape of which has different in planes sectioned by at least two planes including the axially symmetrical axis of the material.
In the present invention, there is provided a seventh light source apparatus wherein in any of the first through fifth light source apparatuses, the cone-like material has an elliptic or rectangular shape in a cross-sectional view sectioned by a plane in which the axially symmetrical axis of said cone-like material is a normal line.
In the present invention, there is provided an eighth light source apparatus wherein in any of the first through seventh light source apparatuses, a first aperture 17 is disposed in front or rear of the cone-like material.
In the present invention, there is provided a first projection type display apparatus which comprises a light source apparatus comprising an elliptic mirror 12; a light source 11 disposed in the vicinity of the first focal point of the elliptic mirror 12; a cone-like material disposed in the vicinity of the second focal point of the elliptic mirror 12 so that the apex of the cone-like material is substantially on the optical axis of the same; and an optical converging means 13, whereby light emitted from the light source 11 is reflected and converged by the elliptic mirror to incident into the cone-like material; the light is emitted through the conical surface of the cone-like material, and enters as divergent light into the optical converging means 13 by which the light is regulated to be substantially parallel light beams;
a color separating and synthesizing optical system comprising a color separating optical system having an angle of incidence of 15.degree.-40.degree., preferably 15.degree.-35.degree., the angle of incidence being formed by the normal line for the optical surface of a color separating means and the optical axis, and a color synthesizing optical system having an angle of incidence of 15.degree.-40.degree., preferably, 15.degree.-35.degree., the angle of incidence being formed by the normal line for the optical surface of a color synthesizing means and the optical axis,
display elements 15 disposed in the light paths extending between the color separating optical system and the color synthesizing optical system, and
a projection optical system.
More specifically, the angle formed by the intersection of the normal line for the optical surface and the optical axis is preferably 30.degree..
In the present invention, there is provided a second projection type display apparatus wherein in the first projection type display apparatus, dichroic mirrors are used as the color separating means of the color separating optical system and the color synthesizing means of the color synthesizing optical system; the display elements 15 are of a transparent and scattering type and are disposed in the light paths for each of color-separated light, and a second converging means 16 is disposed in front or rear of each of the display elements 15 in the light path.
There is provided a third projection type display apparatus wherein in the first or second projection type display apparatus, the cone-like material is a convex cone prism 1.
There is provided a fourth projection type display apparatus wherein in the first or second projection type display apparatus, the cone-like material is a concave cone prism 2.
There is provided a fifth projection type display apparatus wherein in the first or second projection display apparatus, the cone-like material is a convex cone-like reflector 10.
There is provided a sixth projection type display apparatus wherein in the first or second projection type display apparatus, the cone-like material is a concave cone-like reflector 20.
There is provided a seventh projection type display apparatus wherein in the second projection display apparatus, a second aperture means 18 having an opening portion is disposed substantially at the focal point of the second optical converging means 16.
There is provided an eighth projection type display apparatus wherein in any of the first through seventh projection type display apparatuses, the display element 15 comprises a liquid crystal and solidified matrix composite in which a nematic liquid crystal having a positive dielectric anisotropy is dispersed and held in a solidified matrix between a pair of substrates with an electrode whereby the display element 15 exhibits a transparent and scattering type operation mode wherein the refractive index of the solidified matrix is in coincidence with that of the liquid crystal in either state of the application or non-application of a voltage.
In accordance with the present invention, there is provided a first reflection type optical apparatus which comprises an optical apparatus comprising in combination of a light source emitting a plurality of separated light fluxes, a cone-like material and a light converging means 13, and a display element 15 provided with a liquid crystal and solidified matrix composite which has the function of changing a transparent and scattering state of light by an external signal whereby substantially parallel light fluxes emitted from the light source apparatus are passed several times through the liquid crystal and solidified matrix composite.
In accordance with the present invention, there is provided a second reflection type optical apparatus wherein in the first reflection type optical apparatus, a color filter or a color separating and synthesizing optical system is provided for the display element (15) so that colored light is formed.
The light emission part of the light source 11 is in fact a cylindrical body having a finite length. In this case, there is provided a ninth light source apparatus of the present invention wherein in the first light source apparatus, the first focal length of the elliptic mirror 12 is F.sub.1, the second focal length of it is F.sub.2 (F.sub.2 &gt;F.sub.1), the lengths of the light emission part of the light source 11 in the parallel direction and the vertical direction with respect to the rotation symmetric axis of the elliptic mirror 12 are respectively R and S, and the distances .DELTA.R and .DELTA.S of the apex of the cone-like material to the second focal point in the parallel direction and the vertical direction to the rotation symmetric axis of the elliptic mirror 12 are respectively: EQU .DELTA.R.ltoreq.0.25.times.R.times.(F.sub.2 /F.sub.1).sup.2 EQU and EQU .DELTA.S.ltoreq.0.5.times.S.times.(F.sub.2 /F.sub.1).
There is provided the tenth light source apparatus of the present invention wherein in the ninth light source apparatus, the length R of the light emission part of the light source 11 is: EQU 10 mm.gtoreq.R.gtoreq.0.2 mm
and the effective surface area S.sub.A of the light incident side of the cone-like material is represented by: EQU 0.2.times.(R.times.F.sub.2 /F.sub.1).sup.2 .ltoreq.S.sub.A .ltoreq.0.8.times.(F.sub.2 .times.F.sub.1).
Practically, a light source lamp having a range of 1 mm.ltoreq.R.ltoreq.7 mm is generally used.
In accordance with the present invention, there is provided an eleventh light source apparatus wherein in any light source apparatus among the first, the ninth and the tenth light source apparatuses, a relation of EQU f.sub.1.sup.2 /1000.ltoreq.S.sub.A .ltoreq.f.sub.1.sup.2 /40
is satisfied wherein the focal length of the optical converging means 13 is f.sub.1 and the effective cross-sectional area perpendicular to the optical axis of the cone-like material which is a divergent light effective area at the light emission side of the cone-like material or the opening surface area of the aperture 17 is S.sub.B.
In more detailed explanation, an orthogonal coordinate system is considered wherein the rotation symmetric axis of the elliptic mirror is an X-axis, and axes perpendicular to the X-axis at an end point at the first focal position side of the elliptic mirror are respectively a Y-axis and a Z-axis, and a cylindrical shape wherein the length in the X-axis of the light emission part of the light source located at the first focal position of the elliptic mirror is R, and the diameter in the Y-axis and the Z-axis is S. In this case, the image of a light emission part of light source located at the first focal point is formed as an enlarged image of that at a position near the second focal point due to the light converging effect of the elliptic mirror. The sizes R' and S' are approximately expressed as: EQU R'=R.chi.(F.sub.2 /F.sub.1).sup.2 EQU S'=S.chi.(F.sub.2 /F.sub.1)
The above-mentioned relation is shown as a model in FIG. 2b and FIG. 2c where Lcen is the center of the light emission
Accordingly, when the apex of the cone-like material disposed near the second focal position is within the enlarged image of the cylindrical emission part of light source, uniformity of light flux and light converging effect are obtainable.
Preferably, the apex of the cone-like material is arranged in the directions of R and S, which are defined by the following formulas, from the second focal position of the elliptic mirror: EQU .DELTA.R.ltoreq.0.25.times.R'=0.25.times.R.times.(F.sub.2 /F.sub.1).sup.2(A) EQU .DELTA.S.ltoreq.0.5.times.S'=0.5.times.S.times.(F.sub.2 /F.sub.1)(B)
When the elliptic mirror is used as a light converging mirror, the actual light emission part which is not a point light source has its long side which is arranged in the direction of the rotation symmetric axis of the elliptic mirror. For instance, it is approximated as an elongated cylindrical shape having R.gtoreq.2.times.S.
Accordingly, the range of .DELTA.S can be defined by the following formula (C): EQU .DELTA.S.ltoreq.0.25.times.R'=0.25.times.R.times.(F.sub.2 /F.sub.1)(C)
Further, it is preferable that the effective surface area S.sub.A at the light incident side of the cone-like material includes the enlarged image of the light emission part at the second focal position. On the other hand, since the maximum radius of the elliptic mirror in the direction of Y-Z axis is 2.chi.(F.sub.2 .times.F.sub.1).sup.1/2, the upper limit in diameter of the effective surface at the light incident side of the cone-like material is preferably about half of the maximum diameter 2.chi.(F.sub.2 .times.F.sub.1).sup.1/2. Accordingly, it is preferable to satisfy the following condition: EQU 0.2.times.(R.times.F.sub.2 /F.sub.1).sup.2 .ltoreq.S.sub.A .ltoreq.0.8.times.(F.sub.2 .times.F.sub.1) (D)
The collimation index .SIGMA. of the light flux emitted from the light source apparatus is related as tan (.SIGMA.)=.o slashed..sub.0 /f.sub.1 wherein f.sub.1 is the focal length of a condenser lens as the light converging means 13 and .o slashed..sub.0 is the effective aperture in the light emission surface of the cone-like material.
The effective aperture .o slashed..sub.0 in the light emission surface of the cone-like material may be a diameter of the effective cross-sectional area of the cone-like material itself or an opening diameter of the aperture 17.
When a preferred range of collimated light flux obtained from the light source apparatus of the present invention is 2.degree..ltoreq..SIGMA..ltoreq.10.degree. the effective surface area S.sub.B of the light emission surface of the cone-like material satisfies the following formula: EQU f.sub.1.sup.2 /1000.ltoreq.SB.ltoreq.f.sub.1.sup.2 /40 (E)
In accordance with the present invention, there is provided a eleventh light source apparatus of the present invention wherein in above-mentioned light source apparatus, the length of light emission part R, the first focal length F.sub.1, the second focal length F.sub.2, the diagonal length of display element 15 D.sub.s, the focal length of optical converging means 13 f.sub.1 and the refractive index of prism n.sub.p satisfy following relationships: EQU 1 mm.ltoreq.R.ltoreq.7 mm (a.sub.1) EQU 1.5R.ltoreq.F.sub.1 (a.sub.2) EQU 3.ltoreq.F.sub.2 /F.sub.1 .ltoreq.8 (a.sub.3) EQU 25.ltoreq.f.sub.1 /D.sub.s .ltoreq.70 (a.sub.4) EQU 40.ltoreq.f.sub.1.sup.2 /S.sub.B .ltoreq.1000 (a.sub.5) EQU 1.45.ltoreq.n.sub.p .ltoreq.1.65 (a.sub.6)
and EQU 100.degree..ltoreq..alpha..sub.1 .ltoreq.150.degree. or 210.degree..ltoreq..beta..sub.1 .ltoreq.260.degree..
In accordance with the present invention, there is provided a twelfth light source apparatus of the present invention wherein in above-mentioned light source apparatus, the length of light emission part R, the first focal length F.sub.1, the second focal length F.sub.2, the diagonal length of display element 15 D.sub.s, the focal length of optical converging means 13 f.sub.1 and the refractive index of prisms n.sub.p satisfy following relationships: EQU 1 mm.ltoreq.R.ltoreq.7 mm (a.sub.1) EQU 1.5R.ltoreq.F.sub.1 (a.sub.2) EQU 3.ltoreq.F.sub.2 /F.sub.1 .ltoreq.8 (a.sub.3) EQU 25.ltoreq.f.sub.1 /D.sub.s .ltoreq.70 (a.sub.4) EQU 40.ltoreq.f.sub.1.sup.2 /S.sub.B 1000 (a.sub.5)
and EQU 154.degree..ltoreq..alpha..sub.2 .ltoreq.169.degree. or 191.degree..ltoreq..beta..sub.2 .ltoreq.206.degree..